CN107250213B

CN107250213B - Polyamide-imide precursor, polyamide-imide film, and display device comprising same

Info

Publication number: CN107250213B
Application number: CN201580076508.2A
Authority: CN
Inventors: 梁钟源; 郑鹤基
Original assignee: Kolon Industries Inc
Current assignee: Kolon Industries Inc
Priority date: 2014-12-31
Filing date: 2015-12-31
Publication date: 2020-08-07
Anticipated expiration: 2035-12-31
Also published as: KR20160081845A; TWI602854B; US11130844B2; JP2018501377A; CN107250213A; EP3241860A1; EP3241860A4; TW201627355A; JP6410946B2; US20180002487A1; EP3848403A1; KR102227672B1; EP3241860B1

Abstract

The present invention relates to a polyamide-imide precursor, a polyamide-imide obtained by imidizing the polyamide-imide precursor, a polyamide-imide film, and an image display device including the polyamide-imide film. The polyamide-imide precursor comprises in its molecular structure: a first block obtained by copolymerizing monomers including a dianhydride and a diamine; a second block obtained by copolymerizing monomers including an aromatic dicarbonyl compound and the diamine; and a third block obtained by copolymerizing monomers including the aromatic dicarbonyl compound and an aromatic diamine. The dianhydride used to form the first block comprises 2-bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), and the diamine used to form the first and second blocks comprises 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA).

Description

Polyamide-imide precursor, polyamide-imide film, and display device comprising same

Technical Field

The present invention relates to a polyamide-imide precursor, a polyamide-imide film obtained by imidizing the polyamide-imide precursor, and a display device including the polyamide-imide film.

Background

Generally, a Polyimide (PI) film is obtained by molding a polyimide resin into a film, the polyimide resin is a highly heat-resistant resin prepared by solution-polymerizing an aromatic dianhydride and an aromatic diamine or an aromatic diisocyanate to prepare a polyamic acid derivative, and then performing an imidization reaction by ring-closure dehydration at a higher temperature, and the polyimide film is used for various electronic materials such as a semiconductor insulating film, an electrode protective film of TFT-L CD, and a substrate for a flexible printed circuit due to excellent mechanical properties, heat resistance, and electrical insulation properties.

However, polyimide resins generally have brown and yellow colors due to a higher density of aromatic rings, and thus, light transmittance in a visible light region is low and the resins exhibit yellowish colors. Therefore, the light transmittance is lowered and the birefringence is high, which makes it difficult to use the polyimide resin as an optical element.

In order to solve the above limitation, polymerization using purification of monomers and solvents has been attempted, but improvement of light transmittance is not significant. In this regard, in U.S. Pat. No.5053480, when a method using an aliphatic cyclic dianhydride component instead of an aromatic dianhydride is employed to make the resin in the form of a solution or a film, transparency and chroma are improved. However, this is only an improvement of the purification method, and there is still a limitation in the ultimate increase in transmittance. Therefore, a high light transmittance cannot be achieved, but thermal and mechanical deterioration is caused.

In addition, U.S. Pat. Nos. 4595548, 4603061, 4645824, 4895972, 5218083, 5093453, 5218077, 5367046, 5338826, 5986036 and 6232428 and Korean patent application publication No.2003-0009437 disclose a novel structure of polyimide using polyimide having a structure such as-CF-₃Or with substituents such as-O-, -SO₂-or CH₂The aromatic dianhydride and aromatic diamine monomers of the bonding group of (a) to undergo meta bonding instead of the bent structure of para bonding have improved light transmittance and color transparency while the thermal properties are not significantly reduced.

Disclosure of Invention

Technical problem

Accordingly, the present invention is directed to providing a polyamide-imide precursor for forming a colorless transparent film having a low birefringence and excellent mechanical properties and heat resistance. Further, the present invention is directed to a polyamide-imide film prepared by imidizing the polyamide-imide precursor, and an image display device including the polyamide-imide film.

Technical scheme

Accordingly, a preferred first embodiment of the present invention provides a polyamide-imide precursor comprising in its molecular structure: a first block obtained by copolymerizing monomers including a dianhydride and a diamine; a second block obtained by copolymerizing monomers including an aromatic dicarbonyl compound and the diamine; and a third block obtained by copolymerizing monomers including the aromatic dicarbonyl compound and an aromatic diamine. The dianhydride used to form the first block includes 2-bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), and the diamine used to form the first and second blocks includes 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA).

In addition, a preferred second embodiment of the present invention provides a polyamide-imide resin having a structure obtained by imidizing the polyamide-imide precursor of the first embodiment, and a third embodiment provides a polyamide-imide film prepared by imidizing the polyamide-imide precursor of the first embodiment.

In addition, a preferred fourth embodiment of the present invention provides an image display device comprising the polyamide-imide film of the third embodiment.

Advantageous effects

In particular, the polyamide-imide film of the present invention can be used in various fields such as semiconductor insulating films, TFT-L CD insulating films, passivation films, liquid crystal alignment films, optical communication materials, protective films for solar cells, and flexible display substrates.

Drawings

Fig. 1 is an example of a molecular structural formula showing a molecular structure of a polyamide-imide obtained by imidizing a polyamide-imide precursor of the present invention, which contains a first block (a) obtained by polymerizing 6FDA and FFDA, a second block (B) obtained by polymerizing TPC and FFDA, and a third block (C) obtained by polymerizing TPC and TFBD.

Detailed description of the preferred embodiments

Embodiments of the present invention provide a polyamide-imide precursor comprising in its molecular structure: a first block obtained by copolymerizing monomers including a dianhydride and a diamine; a second block obtained by copolymerizing monomers including an aromatic dicarbonyl compound and the diamine; and a third block obtained by copolymerizing monomers including the aromatic dicarbonyl compound and an aromatic diamine. The dianhydride used to form the first block includes 2-bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), and the diamine used to form the first and second blocks includes 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA).

More specifically, an embodiment of the present invention provides a polyamide-imide precursor comprising in its molecular structure: a first block obtained by copolymerizing a dianhydride comprising 2-bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) with a diamine comprising 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA); a second block obtained by copolymerizing an aromatic dicarbonyl compound with a diamine including 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA); and a third block obtained by copolymerizing the aromatic dicarbonyl compound and an aromatic diamine.

When the polyamide-imide precursor of the embodiment of the present invention is formed into a thin film to be used as a substrate or a protective layer of an image display device, the polyamide-imide precursor is obtained by polymerization, which is performed such that three of a first block including an imide bond and a second block and a third block including an amide bond are present in the molecular structure of the polyamide-imide precursor, thereby ensuring excellent thermal and mechanical properties and excellent optical properties. In other words, using the second block and the third block having an amide bond structure can improve poor mechanical properties when the precursor is composed of only an imide structure, thereby finally improving thermal stability, mechanical properties, lower birefringence, and optical characteristics in a balanced manner.

In particular, in an embodiment of the present invention, 6FDA may be used as a dianhydride for forming the first block, thereby improving birefringence and ensuring heat resistance. 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA) containing a benzene ring and having a bulky bond structure (bulk bond structure) in its molecular structure may be used as the diamine forming the first block and the second block, thereby effectively preventing a decrease in optical properties caused by the aromatic dicarbonyl compound provided to the second block and the third block.

In the embodiment of the present invention, in order to improve the yellow index and the birefringence, the total content of the first block and the second block may be preferably 20 mol% to 80 mol% based on the total block copolymer of which the total is 100 mol, and may be more preferably 40 mol% to 60 mol% in order to prevent deterioration of mechanical properties. When the total content of the first block and the second block is less than 20 mol%, mechanical properties may be improved but heat resistance may be reduced and optical properties such as light transmittance and yellow index may be rapidly reduced due to a relative increase in the molar ratio of the third block. When the total content of the first block and the second block is more than 80 mol%, since the improvement of mechanical properties is insignificant, a twisting and tearing phenomenon may occur during the manufacturing process of the display.

In addition, in an embodiment of the present invention, the molar ratio of the first block and the second block is preferably from 2:8 to 8: 2. When the content of the first block is outside the above range, thermal stability and mechanical properties may be improved, but optical properties such as yellow index or light transmittance may be reduced and birefringence may be increased, which makes it difficult to apply the precursor to an optical device. On the other hand, when the content of the second block is outside the above range, the effect of improving thermal stability and mechanical properties may not be expected.

In an embodiment of the present invention, the aromatic dicarbonyl compound used to form the second block and the third block may be one or more selected from the group consisting of terephthaloyl chloride (TPC), terephthalic acid, isophthaloyl chloride and 4,4' -biphenyldicarbonyl chloride, and more preferably, may be one or more selected from the group consisting of terephthaloyl chloride (TPC) and isophthaloyl chloride.

In addition, the aromatic diamine used to form the third block may be selected from 2, 2-bis (4- (4-aminophenoxy) phenyl) Hexafluoropropane (HFBAPP), bis (4- (4-aminophenoxy) phenyl) sulfone (BAPS), bis (4- (3-aminophenoxy) phenyl) sulfone (BAPSM), 4' -diaminodiphenyl sulfone (4DDS), 3' -diaminodiphenyl sulfone (3DDS), 2-bis (4- (4-aminophenoxy) phenylpropane) (6HMDA), 4' -diaminodiphenyl propane (6HDA), 4' -diaminodiphenyl Methane (MDA), 4' -diaminodiphenyl sulfide (4,4' -thioaniline), 4' -diaminodiphenyl diethylsilane, 4,4' -diaminodiphenylsilane (44DDS), 4' -diaminodiphenyl N-methylamine, 4' -diaminodiphenyl N-phenylamine, 1, 3-phenylenediamine (m-PDA), 1, 2-phenylenediamine (o-PDA), 4' -diaminodiphenylether (44' ODA), one or more diamines having a flexible group selected from 3,3' -diaminodiphenyl ether (33' ODA), 2, 4-diaminodiphenyl ether (24' ODA), 3,4' -diaminodiphenyl ether (34' ODA), 1, 3-bis (4-aminophenoxy) benzene (TPE-R), 1, 3-bis (3-aminophenoxy) benzene (APB), 4' -bis (3-aminophenoxy) biphenyl and 4,4' -bis (4-aminophenoxy) biphenyl (BAPB).

In an embodiment of the present invention, the aromatic diamine used to form the third block may be different from the diamine used to form the first and second blocks, i.e., 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA). When the third block contains FFDA, the structure thereof may be the same as that of the second block, so that the desired mechanical properties resulting from the three-component structure cannot be ensured. Likewise, when the aromatic diamine used to form the third block is replaced with FFDA in the first and second blocks, the structures of the second and third blocks may become the same, which causes a decrease in optical properties and an increase in birefringence. In other words, preferably, carbazole-based diamine FFDA containing a benzene ring of a bulky structure is contained in the first and second blocks. In order to ensure the desired mechanical properties, it is preferred to use an aromatic diamine in the third block.

In addition, when a structure derived from an aromatic dicarbonyl compound is included in the molecular structure, high thermal stability and mechanical properties can be easily achieved, but birefringence may be high due to a benzene ring in the molecular structure. Therefore, in the embodiment of the present invention, more preferably, the aromatic diamine used to form the third block may have a molecular structure including a flexible group from the viewpoint of preventing a decrease in birefringence caused by the aromatic dicarbonyl compound. In particular, the aromatic diamine may preferably have a long flexible group and a substituent present in a meta position, and may preferably be one or more aromatic diamines selected from bis (4- (3-aminophenoxy) phenyl) sulfone (BAPSM), 4' -diaminodiphenyl sulfone (4DDS), and 2, 2-bis (4- (4-aminophenoxy) phenyl) Hexafluoropropane (HFBAPP) in order to achieve excellent birefringence.

In an embodiment of the present invention, the polyamide imide precursor comprises in its molecular structure: a first block obtained by copolymerizing a dianhydride comprising 2-bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) with a diamine comprising 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA); a second block obtained by copolymerizing an aromatic dicarbonyl compound with a diamine including 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA); and a third block obtained by copolymerizing the aromatic dicarbonyl compound and an aromatic diamine through polymerization of a monomer. The polyamide-imide precursor preferably has a weight average molecular weight of 60,000 to 70,000 measured using GPC (gel permeation chromatography), and a viscosity of 400 to 600ps in a solid concentration range of about 20 to 25 wt%.

Meanwhile, embodiments of the present invention may provide a polyamide-imide resin having a structure obtained by close dehydration (i.e., imidization) of the polyamide-imide precursor, or may provide a polyamide-imide film prepared by imidizing the polyamide-imide precursor. In order to prepare a polyamide-imide resin or a polyamide-imide film using the polyamide-imide precursor, the following imidization step may be performed.

First, a polyamide-imide precursor solution was prepared by copolymerizing < dianhydride and aromatic dicarbonyl compound > and < diamine and aromatic diamine > satisfying the above conditions of the present invention at an equivalent ratio of 1:1 based on the total molar ratio of the monomers. The conditions of the polymerization reaction are not particularly limited, but the polymerization reaction is preferably carried out at-10 ℃ to 80 ℃ for 2 to 48 hours in an inert atmosphere such as nitrogen or argon.

Solvents may be used for the solution polymerization of the monomers. The solvent is not particularly limited as long as it is a known reaction solvent, but one or more polar solvents selected from the group consisting of m-cresol, N-methyl-2-pyrrolidone (NMP), Dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), acetone, and ethyl acetate may be preferably used. In addition, a low boiling point solution such as Tetrahydrofuran (THF) and chloroform, or a low absorption solvent such as γ -butyrolactone may be used.

In addition, the content of the solvent is not particularly limited. However, in order to obtain an appropriate molecular weight and viscosity of the polyamide-imide precursor solution, the content of the solvent may preferably be 50 to 95% by weight, more preferably 70 to 90% by weight, based on the total content of the polyamide-imide precursor solution.

Subsequently, a known imidization method may be appropriately selected to imidize the resulting polyamide-imide precursor solution. For example, a thermal imidization method or a chemical imidization method may be applied, or a thermal imidization method and a chemical imidization method may be applied in combination.

In the chemical imidization method, a dehydrating agent represented by an acid anhydride such as acetic anhydride and an imidization catalyst represented by a tertiary amine such as isoquinoline, β -methylpyridine and pyridine are added to a polyimide-imide precursor solution to perform a reaction, and in the thermal imidization method, the polyamide-imide precursor solution is slowly heated at a temperature ranging from 40 ℃ to 300 ℃ for 1 to 8 hours to perform a reaction.

In the embodiment of the present invention, a complex imidization method using a combination of a thermal imidization method and a chemical imidization method may be used as an example of the method for preparing the polyamide-imide film. More specifically, the complex imidization process may be performed through a series of processes. In these processes, a dehydrating agent and an imidization catalyst are added to a polyamide-imide precursor solution to be cast onto a support, and then heated to 80 ℃ to 200 ℃, preferably 100 ℃ to 180 ℃, to activate it. The resulting material is partially cured and dried, and then heated at 200 ℃ to 400 ℃ for 5 to 400 seconds.

In addition, in an embodiment of the present invention, the obtained polyamide-imide precursor solution may be imidized, and the solution after imidization may be added to a second solvent, followed by precipitation, filtration and drying, thereby obtaining a polyamide-imide resin solid. The obtained polyamide-imide resin solid may be dissolved in a first solvent for film formation to prepare a polyamide-imide film. For the drying conditions after the filtration of the polyamide-imide resin solid, it is preferable that the temperature is 50 ℃ to 120 ℃ for 3 to 24 hours in view of the boiling point of the second solvent. Casting may be performed, and the temperature may be slowly increased in the temperature range of 40 to 400 ℃ over 1 minute to 8 hours, thereby implementing a film forming process.

In addition, the first solvent may be the same as the solvent used during the polymerization of the polyamide-imide precursor solution. As the second solvent, in order to obtain the polyamide-imide resin solid, a solvent having a polarity lower than that of the first solvent, that is, one or more solvents selected from water, alcohols, ethers, and ketones may be used. The content of the second solvent is not particularly limited, but is preferably 5 to 20 times by weight based on the weight of the polyamide-imide precursor solution.

In the embodiment of the present invention, in order to remove the residual thermal history and residual stress in the film, the resulting polyamide-imide film may be subjected to additional heat treatment again. The temperature of the additional heat treatment process is preferably 300 ℃ to 500 ℃ and the heat treatment time is preferably 1 minute to 3 hours. The residual volatile content of the film after heat treatment may be 5% or less, preferably 3% or less. As a result, the heat-treated film finally exhibits very stable thermal properties.

In the embodiment of the present invention, the thickness of the polyamide-imide film is not particularly limited, but is preferably in the range of 5 to 100 μm, more preferably 9 to 15 μm.

The polyamide-imide film according to an embodiment of the present invention exhibits the following optical properties, including: a birefringence (n) defined by TE (transverse electric field) -TM (transverse magnetic field) is 0.030 or less, preferably 0.019 or less, based on a film thickness of 10 to 50 μm; a light transmittance measured at 550nm of 88% or more, preferably 90% or more, more preferably 90.68% or more; the yellow index is 5 or less, and thus can be used for a substrate or a protective layer of an optical device such as a display.

In addition, in the polyimide film according to the present invention, a coefficient of linear thermal expansion (CTE) measured repeatedly twice at 50 ℃ to 250 ℃ using a thermomechanical analysis method (TMA method) is 60 ppm/c or less, preferably 44.50 ppm/c or less, more preferably 40.37 ppm/c or less, more preferably 37.12 ppm/c or less, based on a film thickness of 10 μm to 50 μm, and an elongation at break measured based on ASTM D882 is 5% or more, preferably 5.31% or more, more preferably 6.11% or more. Therefore, in the manufacturing process of the display, bending or deformation does not easily occur even under severe process temperature or sudden temperature change, thereby exhibiting excellent yield.

In addition, since the present invention includes the above polyimide film, an image display device having excellent optical and physical properties and a high manufacturing yield can be provided.

A better understanding of the present invention may be obtained through the following examples which are set forth to illustrate, but are not to be construed to limit the present invention.

Example 1

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 398.628g of N-methyl-2-pyrrolidone (NMP) was added while introducing nitrogen, and 49.207g (0.128mol) of 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA) was dissolved. Subsequently, 10.247g (0.032mol) of 2-bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) was added and reacted for 2 hours, followed by addition of 10.247g (0.032mol) of bis (trifluoromethylbenzidine) (TFDB). After the temperature of the solution was maintained at 10 ℃ or lower, 25.987g (0.128mol) of terephthaloyl chloride (TPC) was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 120 poise.

After the reaction was completed, the resulting solution was coated on a stainless steel plate, cast to 10 to 20 μm, dried in hot air at 80 ℃ for 20 minutes, dried at 120 ℃ for 20 minutes, and dried at a constant temperature of 300 ℃ for 10 minutes, slowly cooled, and separated from the stainless steel plate, thereby preparing a polyamide-imide film having a thickness of 20 μm.

Example 2

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 386.301g of N-methyl-2-pyrrolidone (NMP) was added while passing nitrogen, and 30.754g (0.08mol) of FFDA was dissolved. Subsequently, 14.216g (0.032mol) of 6FDA were added and reacted for 2 hours, followed by 25.618g (0.08mol) of TFDB. After the temperature of the solution was maintained at 10 ℃ or lower, 25.987g (0.128mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 640 poise.

Subsequently, a polyamide-imide film was prepared according to the same procedure as in example 1.

Example 3

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 401.714g of N-methyl-2-pyrrolidone (NMP) was added while passing nitrogen, and 19.606g (0.051mol) of FFDA was dissolved. Subsequently, 15.105g (0.034mol) of 6FDA were added and reacted for 2 hours, followed by 38.107g (0.119mol) of TFDB. After the temperature of the solution was maintained at 10 ℃ or lower, 27.611g (0.136mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 1100 poise.

Example 4

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 390.410g of N-methyl-2-pyrrolidone (NMP) was added while passing nitrogen, and 36.905g (0.096mol) of FFDA was dissolved. Subsequently, 14.216g (0.032mol) of 6FDA were added and reacted for 2 hours, followed by 20.495g (0.064mol) of TFDB. After the temperature of the solution was maintained at 10 ℃ or lower, 25.987g (0.128mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 610 poise.

Example 5

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 405.849g of N-methyl-2-pyrrolidone (NMP) was added while passing nitrogen, and 36.905g (0.096mol) of FFDA was dissolved. Subsequently, 21.324g (0.048mol) of 6FDA were added and reacted for 2 hours, followed by 20.495g (0.064mol) of TFDB. After the temperature of the solution was maintained at 10 ℃ or lower, 22.738g (0.112mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 590 poise.

Example 6

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 394.957g of N-methyl-2-pyrrolidone (NMP) was added while introducing nitrogen, and 34.599g (0.09mol) of FFDA was dissolved. Subsequently, 26.655g (0.06mol) of 6FDA was added and reacted for 2 hours, and 12.914g (0.06mol) of TFDB was added. After the temperature of the solution was maintained at 10 ℃ or lower, 18.272g (0.09mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 550 poise.

Example 7

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 398.288g of N-methyl-2-pyrrolidone (NMP) was added while passing nitrogen, and 31.139g (0.081mol) of FFDA was dissolved. Subsequently, 23.99g (0.054mol) of 6FDA was added and reacted for 2 hours, and 27.999g (0.054mol) of 2, 2-bis (4- (4-aminophenoxy) phenyl) Hexafluoropropane (HFBAPP) was added. After the temperature of the solution was maintained at 10 ℃ or lower, 16.445g (0.081mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 420 poise.

Comparative example 1

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 338.101g of N-methyl-2-pyrrolidone (NMP) was added while introducing nitrogen, and 39.212g (0.102mol) of FFDA was dissolved. After the temperature of the solution was maintained at normal temperature, 45.314g (0.102mol) of 6FDA was added and reacted for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 120 poise.

Comparative example 2

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 399.466g of N-methyl-2-pyrrolidone (NMP) was added while introducing nitrogen, and 65.353g (0.17mol) of FFDA was dissolved. After the temperature of the solution was maintained at 10 ℃ or lower, 34.513g (0.17mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 150 poise.

Comparative example 3

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 397.530g of N-methyl-2-pyrrolidone (NMP) was added while passing nitrogen, and 41.630g (0.13mol) of TFDB was dissolved. After the temperature of the solution was maintained at normal temperature, 57.753g (0.13mol) of 6FDA was added and reacted for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 1750 poise.

Comparative example 4

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 397.670g of N-methyl-2-pyrrolidone (NMP) was added while passing nitrogen, and 60.844g (0.19mol) of TFDB was dissolved. After the temperature of the solution was maintained at 10 ℃ or less, 38.574g (0.19mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 2100 poise.

Comparative example 5

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 388.660g of N-methyl-2-pyrrolidone (NMP) was added while passing nitrogen, and 9.611g (0.025mol) of FFDA was dissolved. After the temperature of the solution was kept at room temperature, 32.023g (0.1mol) of TFDB was added, and after 2 hours, 55.531g (0.125mol) of 6FDA was added. The reaction was carried out for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 1100 poise.

Comparative example 6

In a 500ml reactor equipped with a stirrer, nitrogen syringe, dropping funnel, temperature controller and condenser, 398.290g of N-methyl-2-pyrrolidone (NMP) were added while passing nitrogen, and 24.027g (0.0625mol) of FFDA were dissolved. After the temperature of the solution was maintained at ordinary temperature, 20.014g (0.0625mol) of TFDB was added, and after 2 hours, 55.531g (0.125mol) of 6FDA was added. The reaction was carried out for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 550 poise.

Comparative example 7

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 407.920g of N-methyl-2-pyrrolidone (NMP) was added while introducing nitrogen, and 38.443g (0.1mol) of FFDA was dissolved. After the temperature of the solution was kept at room temperature, 8.006g (0.025mol) of TFDB was added, and after 2 hours, 55.531g (0.125mol) of 6FDA was added. The reaction was carried out for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 110 poise.

Comparative example 8

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 438.887g of N-methyl-2-pyrrolidone (NMP) was added while introducing nitrogen, and 26.141g (0.068mol) of FFDA was dissolved. Subsequently, 30.209g (0.068mol) of 6FDA were added and reacted for 2 hours, followed by 32.663g (0.102mol) of TFDB. After the temperature of the solution was maintained at 10 ℃ or lower, 20.708g (0.102mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 920 poise.

Comparative example 9

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 421.425g of N-methyl-2-pyrrolidone (NMP) was added while passing nitrogen, and 54.439g (0.17mol) of TFDB was dissolved. Subsequently, 30.209g (0.068mol) of 6FDA were added and reacted for 2 hours. After the temperature of the solution was maintained at 10 ℃ or lower, 20.708g (0.102mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 710 poise.

Comparative example 10

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 465.081g of N-methyl-2-pyrrolidone (NMP) was added while introducing nitrogen, and 65.353g (0.17mol) of FFDA was dissolved. Subsequently, 30.209g (0.068mol) of 6FDA were added and reacted for 2 hours. After the temperature of the solution was maintained at 10 ℃ or lower, 20.708g (0.102mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 220 poise.

Comparative example 11

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 417.187g of N-methyl-2-pyrrolidone (NMP) was added while introducing nitrogen, and 29.217g (0.076mol) of FFDA was dissolved. 36.506g (0.114mol) of TFDB were dissolved while maintaining the temperature. After the temperature of the solution was maintained at 10 ℃ or less, 38.574g (0.190mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 530 poise.

Comparative example 12

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 420.722g of N-methyl-2-pyrrolidone (NMP) was added while introducing nitrogen, and 46.113g (0.144mol) of TFDB was dissolved. Subsequently, 15.993g (0.036mol) of 6FDA were added and reacted for 2 hours, followed by 13.839g (0.036mol) of FFDA. After the temperature of the solution was maintained at 10 ℃ or lower, 29.235g (0.144mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 325 poise.

Comparative example 13

In a 500ml reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller and a condenser, 450.566g of N-methyl-2-pyrrolidone (NMP) was added while introducing nitrogen, and 58.433g (0.152mol) of FFDA was dissolved. Subsequently, 11.180g (0.038mol) of BPDA were added and reacted for 6 hours, followed by 12.169g (0.038mol) of TFDB. After the temperature of the solution was maintained at 10 ℃ or lower, 30.859g (0.152mol) of TPC was added and reacted at a lower temperature for 1 hour, and then the temperature was raised to normal temperature, followed by reaction for 18 hours, thereby obtaining a polyamide-imide precursor solution having a solid concentration of 20% by weight and a viscosity of 280 poise.

< measurement >

The physical properties of the polyamide-imide films prepared in examples and comparative examples were evaluated using the following methods. The results are shown in tables 1 and 2 below.

(1) Viscosity: the viscosity was measured twice at 25rpm and 50rpm using a Brookfield viscometer (RVDV-II + P) Scandal 6 or 7 to obtain an average value.

(2) Measurement of light transmittance: the light transmittance was measured three times at 550nm using an ultraviolet spectrophotometer (Konica Minolta, CM-3700d), and the average value is shown in Table 1.

(3) Measurement of yellowness index (Y.I.): the yellowness index was measured according to ASTM E313 using an ultraviolet spectrophotometer (Konica Minolta, CM-3700 d).

(4) Measurement of birefringence: the birefringence was measured three times at 532nm in each of the TE (transverse electric field) and TM (transverse magnetic field) modes using a birefringence analyzer (Prism Coupler, Sairon SPA4000) to obtain an average value, and the (TE mode) - (TM mode) were taken as the birefringence values.

(5) Measurement of Coefficient of Thermal Expansion (CTE) according to TMA method, linear thermal expansion coefficient was measured twice at 50 ℃ to 250 ℃ using TMA (TA Instrument Company, Q400). The size of the sample was 4mm 3524 mm, the load was 0.02N, and the temperature rise rate was 10 ℃/min.

(6) Measurement of elongation at break (%). elongation at break is measured according to ASTM-D882 using Instron 5967. at the time of measurement, the sample size is 15mm × 100mm, the load cell is 1KN, and the tensile rate is 10 mm/min.

[ Table 1]

1) When the monomers are the same, the order in which the monomers are described is the order in which they are added.

2) A ═ first block, B ═ second block, and C ═ third block

[ Table 2]

From tables 1 and 2, it can be confirmed that in examples 1 to 7, the light transmittance, the yellow index and the birefringence are similar to those in comparative examples 1,3 and 5 to 7 (conventional polyimide substrates), and the thermal expansion coefficient is low. Therefore, the optical properties and heat resistance were excellent, and the elongation at break was the same as or higher than those of comparative examples 2 and 4 (polyamide), indicating that examples 1 to 7 had excellent mechanical properties. In particular, it can be confirmed that, as in example 7, when diamine HFBAPP having a longer flexible group is added, the birefringence and elongation at break are further improved.

Further, as in comparative examples 8 and 9, when the second block obtained by copolymerizing FFDA with an aromatic dicarbonyl compound is not included in the molecular structure, there is a limit to the optical properties (decrease in light transmittance, increase in difference in birefringence). As in comparative examples 10 and 11, when the first block or the second block is not formed, the heat resistance (comparative example 10) or the birefringence (comparative example 11) is lowered depending on the type of the block that is not formed. Further, as in comparative example 12, when FFDA, which is a diamine for forming the first block and the second block, is not contained, the heat resistance is poor. As in comparative example 13, when 6FDA as a dianhydride for forming the first block is not contained, the value of the yellow index is found to be undesirable.

Industrial applicability

The present invention relates to a polyamide-imide precursor and is suitable for a polyamide-imide obtained by imidizing the polyamide-imide precursor, a polyamide-imide film, and an image display device including the polyamide-imide film.

Claims

1. A polyamide imide precursor comprising in its molecular structure:

a first block obtained by copolymerizing monomers including a dianhydride and a diamine;

a second block obtained by copolymerizing monomers including an aromatic dicarbonyl compound and the diamine; and

a third block obtained by copolymerizing monomers including the aromatic dicarbonyl compound and an aromatic diamine,

wherein the dianhydride used to form the first block comprises 2-bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA), the diamine used to form the first and second blocks comprises 9, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA),

wherein the aromatic diamine used to form the third block is different from the diamine used to form the first and second blocks, that is, 9-bis (3-fluoro-4-aminophenyl) fluorene (FFDA), and

wherein the aromatic diamine used to form the third block is selected from the group consisting of 2, 2-bis (4- (4-aminophenoxy) phenyl) Hexafluoropropane (HFBAPP), bis (4- (4-aminophenoxy) phenyl) sulfone (BAPS), bis (4- (3-aminophenoxy) phenyl) sulfone (BAPSM), 4' -diaminodiphenyl sulfone (4DDS), 3' -diaminodiphenyl sulfone (3DDS), 2-bis (4- (4-aminophenoxy) phenylpropane) (6HMDA), 4' -diaminodiphenyl propane (6HDA), 4' -diaminodiphenyl Methane (MDA), 4' -diaminodiphenyl sulfide (4,4' -thiodiphenylamine), 4' -diaminodiphenyl diethylsilane, 4,4' -diaminodiphenylsilane (44DDS), 4' -diaminodiphenyl N-methylamine, 4' -diaminodiphenyl N-phenylamine, 1, 3-phenylenediamine (m-PDA), 1, 2-phenylenediamine (o-PDA), 4' -diaminodiphenyl ether (44' ODA), 3' -diaminodiphenyl ether (33' ODA), 2, 4-diaminodiphenyl ether (24' ODA), 3,4' -diaminodiphenyl ether (34' ODA), 1, 3-bis (4-aminophenoxy) benzene (TPE-R), 1, 3-bis (3-aminophenoxy) benzene (APB), 4' -bis (3-aminophenoxy) biphenyl, bistrifluoromethylbenzidine (TFDB) and 4, one or more of 4' -bis (4-aminophenoxy) biphenyl (BAPB),

wherein the total content of the first block and the second block is 30 to 80 mol% based on the total block copolymer of which the total is 100 mol;

wherein the molar ratio of the first block to the second block is from 8:2 to 2: 8.

2. The polyamide imide precursor as claimed in claim 1 wherein the aromatic dicarbonyl compound used to form the second and third blocks is one or more selected from the group consisting of terephthaloyl chloride (TPC), terephthalic acid, isophthaloyl chloride and 4,4' -biphenyldicarbonyl chloride.

3. A polyamide-imide resin having a structure obtained by imidizing the polyamide-imide precursor of any one of claims 1 to 2.

4. A polyamide-imide film prepared by imidizing the polyamide-imide precursor of any one of claims 1 to 2.

5. The polyamide-imide film according to claim 4 wherein the polyamide-imide film has a birefringence (n) defined by TE (transverse electric field) -TM (transverse magnetic field) of 0.030 or less.

6. The polyamide-imide film of claim 4 wherein the polyamide-imide film has a coefficient of linear thermal expansion (CTE) of 60ppm/° C or less, measured using a thermomechanical analysis method (TMA method) repeated twice at 50 ℃ to 250 ℃, based on a film thickness of 10 μm to 50 μm.

7. The polyamide-imide film according to claim 4 wherein the polyamide-imide film has a light transmittance of 88% or more measured at 550nm and a yellow index of 5 or less, based on a film thickness of 10 to 50 μm.

8. The polyamide imide film according to claim 4 wherein the polyamide imide film has an elongation at break of 5% or more as measured by ASTM D882 at a film thickness of 10 to 50 μm.

9. An image display apparatus comprising:

the polyamide imide film of claim 4.